Nano technology is becoming the next frontier of development and advancement in science. This has been clearly indicated by the R&D investments in Nano-applications in the past few years. Currently the most advanced areas of Nano-technology are the field of genetics and the field of nano-structure growth. The Nano-structure growth field has been fueled mainly by advances in the area of materials. One such area is the area of Carbon Nanotubes and semi-conducting Nanowires. Even though interest is high in the nano-technology area, the development of equipments for the manufacture of such material has lagged, as the market is not yet large enough to attract leading equipment vendors into this area.
Typically Carbon Nanotubes are grown in the labs through four different processes. They are:                a) Electric arc discharge techniques involving the generation of an electric arc between two graphite electrodes, one of which is usually filled with a catalyst metal powder (e.g., iron, nickel, cobalt), in a Helium atmosphere.        b) Laser ablation methods using a laser to evaporate a graphite target which is usually filled with a catalyst metal powder.        c) Chemical vapour deposition processes utilising nanoparticles of a metal catalyst to react with a hydrocarbon gas at temperatures of 500-900° C. to produce carbon nanotubes. In these chemical vapour deposition processes, the catalyst decomposes the hydrocarbon gas to produce carbon and hydrogen. The carbon precipitates out from the catalyst to form the carbon nanotube.        d) A variant of the chemical vapour deposition is plasma enhanced chemical vapour deposition in which vertically aligned carbon nanotubes can easily be grown using the plasma over a heated subsrate to decompose the hydrocarbon gas to produce the carbon. The carbon precipitates out from the catalyst to form the carbon nanotube.        
The arc discharge and laser ablation techniques tend to produce an ensemble of carbonaceous material which contain nanotubes (30-70%), amorphous carbon and carbon particles. The nanotubes are then extracted by some form of purification process before being manipulated into place for specific applications.
In the Chemical Vapor deposition based growth and the Plasma enhanced Chemical Vapor Deposition based growth, the catalyst acts as a ‘template’ from which the carbon nanotube is formed, and, by controlling the catalyst size and reaction time, one can easily tailor the nanotube diameter and length, respectively. Semiconducting nanowires of different elements can also be grown using chemical vapour deposition via the appropriate feedstock gases or elemental vapour.
Carbon tubes, in contrast to a solid carbon filament or other semiconducting nanowires, will tend to form when the catalyst particle is ˜50 nm or less. In filament graphitic sheet form, in a nano structure, there will be an enormous percentage of ‘edge’ atoms. These edge atoms have dangling bonds which makes the structure energetically unfavourable and unstable. The closed structure of tubular graphene shells is a stable, dangling-bond free solution to this problem, and hence the carbon nanotube is the energetically favourable and stable structural form of carbon at these tiny dimensions.